1. Field of the Invention
This invention relates to a scroll fluid apparatus which can serve as a compressor for increasing the pressure of air or other gases, a refrigerant compressor adapted for use with freezing apparatus, showcases or refrigerating apparatus, a refrigerant compressor adapted for use with air conditioning systems or room cooling apparatus, or an expansion device adapted for enabling the Rankine cycle to take place or expanding high pressure gas to a predetermined pressure level to obtain power therefrom.
2. Description of the Prior Art
U.S. Pat. Nos. 3,884,599 and 3,924,977 disclose means for providing an axial seal to a pair of scroll members by maintaining the forward end of the wrap of one scroll member in contact with the end plate of the other scroll member to prevent the leakage of gas from between the two scroll members.
In the means disclosed in these documents, the gas drawn from the discharge region defined by the two scroll members is applied to the back (the surface opposite to the surface from which the wrap extends) of one scroll member so as to force one scroll member tightly against the other scroll member. The gas applied to the back of the scroll member is directed to a portion of the back which is very small in area. In the structural arrangement shown in these documents, a thrust corresponding in amount to the axially displacing force exerted by the gas is brought to bear upon a bearing 47 (See FIGS. 8 and 34 of U.S. Pat. No. 3,884,599) and main shaft bearings 122, 293 and 343 (See FIGS. 8, 34 and 38 of the same specification), so that a heavy thrust load is applied to each of these bearings.
U.S. Pat. Nos. 3,994,633 and 3,994,636 disclose scroll members enclosed by a housing having a housing chamber into which a fluid is introduced from a pressure source located outside the scroll fluid apparatus, so that the fluid can be applied to the back (the surface opposite to the surface from which the wrap extends) of one scroll member to thereby force the same tightly against the other scroll member. The aformentioned arrangement enables the thrust load applied to each bearing to be eliminated. However, some disadvantages are associated with this type of scroll fluid apparatus. One of them is that a separate pressure source must be provided outside the apparatus. Another disadvantage is that, if the scroll fluid apparatus is used as a refrigerant compressor which requires strict caution to be exercised to avoid incorporation of a non-condensing gas in the refrigerant, means must be provided to ensure that the two scroll members are hermetically sealed to prevent the gas introduced into the housing chamber from being incorporated into the gas to be compressed by the scroll members.